The procedure that transforms raw data into useful information is called processing. To perform this transformation, the computer uses two components: the processor and memory.
The processor is like the brain of the computer; it organizes and carries out instructions that come from either the user or the software. In a personal computer the processor usually consists of one or more specialized chips, called microprocessors, which are slivers of silicon or other material etched with many tiny electronic circuits. To process data or complete an instruction from a user or a program the computer passes electricity through the circuits. The microprocessor is plugged into the computer’s motherboard. The mother-board is a rigid rectangular card containing the circuitry that connects the processor to the other hardware. The motherboard is an example o f a circuit the microprocessor board. In most personal computers, many internal devices such as video cards, sound cards, disk controllers, and other devices—are housed on their own smaller circuit boards, which attach to the motherboard.
In many newer computers, these devices are built directly into the motherboard. Some newer microprocessors are large and complex enough to require their own dedicated circuit boards, which plug into a special slot in the motherboard. You can think of the motherboard as the master circuit board in a computer.
A personal computer’s processor is usually a single chip or a set of chips contained on a circuit board. In some powerful computers, the processor consists of many chips and the circuit boards on which they are mounted. In either case, the term control processing unit (CPU) refers to a computer’s processor. People often refer to computer systems by the type of CPU they contain. A "Pentium 4” system, for example, uses a Pentium 4 microprocessor as its CPU.